Keyed hash algorithms provide authenticated hash codes by combining a
secret key with the data to process. The recipient can validate the
hash code only if he knows the secret key.

All keyed hash algorithm implementations inherit from this abstract
class, which extends the HashAlgorithm class.
Implementation classes are instantiated using the Create(
) method, which accepts the name of an implementation as a
System.String argument. The default implementation
class is created if no name is specified; the system administrator
determines the default class.

In addition to the members defined by the parent class,
KeyedHashAlgorithm implements the
Key property, which gets and sets the value of the
secret key, expressed as a System.Byte array.